Collaborative Research: Verification of Atmospheric Mercury Redox Rates

该项目中的跨机构合作调查人员将通过定量测量二价汞化合物，提供参与大气中汞氧化的化合物的新的综合数据集，二价汞化合物是汞的更易溶于水的形式。汞以元素状态排放到大气中，它与大气中的氧化剂发生各种反应，形成二价形式，但关于哪些氧化剂种类以及这些反应发生的速度存在许多不确定因素。该项目的主要目标是使用这些新的形态汞测量方法，以及以前的测量方法，对盐湖城地区靠近一个镁矿设施(美国镁)的汞的形态和采样羽流的基本预算进行定量表征。在该项目的整个过程中，将对两名研究生进行培训，项目组计划向决策者提供有关汞化学及其对人类健康影响的最新信息。该团队还计划与州监管机构接触，以潜在地扩大所获得的知识的社会效益。最近关于标准测量技术的一项发现揭示了系统性的低偏差，几乎影响到以前对二价汞的所有测量。由该课题组开发、测试和以前部署的双通道连续汞测量系统可以在没有这种低偏差的情况下进行二价汞测量。这项工作有三个具体目标：(1)开展为期一年的元素汞和二价汞、相关氧化剂和其他化学和气象变量的测量活动；(2)使用零维F0AM模型来确定哪些汞的化学机制和反应速率将模型测量误差降至最低；以及(3)用F0AM参数更新GEOS-Chem的汞氧化机理，以最大限度地减少GEOS-化学模型测量误差。这项工作的结果将加强我们对汞化学和受汞化学影响的化学物种的了解，包括卤素、臭氧和氮氧化物。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The cross-institutional collaborative investigators in this project will provide a new comprehensive dataset of compounds involved in the oxidation of mercury in the atmosphere by quantitatively measuring divalent mercury compounds, which are the more water-soluble forms of mercury. Mercury is emitted into the atmosphere in the elemental state, which undergoes various reactions with atmospheric oxidants into the divalent form, but there exist many uncertainties about which oxidant species and what rates these reactions occur. The primary objective of this project is to use these new measurements of speciated mercury, along with previous measurements, to quantitatively characterize both the speciation of mercury and the radical budget of sampled plumes in the Salt Lake City region nearby a magnesium mining facility (U.S. Magnesium). Two graduate students will be trained over the course of this project, and the project team plans on providing policy makers with updated information pertaining to mercury chemistry and the impacts on human health. The team also has plans to engage with state regulators to potentially extend the societal benefits of the knowledge gained.A recent discovery pertaining to standard measurement techniques has revealed a systematic low bias that affects nearly all previous measurements of divalent mercury. The dual-channel continuous mercury measurement system developed, tested, and previously deployed by this research group can make divalent mercury measurements without this low bias. The work has three specific aims: (1) to conduct a year-long measurement campaign of elemental and divalent mercury, related oxidants, and other chemical and meteorological variables; (2) use the zero-dimensional F0AM model to identify which mercury chemical mechanisms and reaction rates minimize model-measurement discrepancies; and (3) update GEOS-Chem’s mercury oxidation mechanism with the F0AM parameters to minimize GEOS-Chem model-measurement discrepancies. Results from this work will enhance our understanding of mercury chemistry and chemical species affected by mercury chemistry, including halogens, ozone, and nitrogen oxides.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.